Recently, attempts have been made to perform electronic commerce (e-commerce) transactions using IC (Integrated Circuit) cards via networks. Since an IC has a data-writable (rewritable) memory, a single IC card is repeatedly used. Using this characteristic, a value is stored on an IC card. By rewriting the value, the IC card is used as electronic money for settling a payment for a commerce transaction.
Compared with known magnetic cards, IC cards are more failure-resilient and store greater amount of information. Such IC cards are thus used in online e-commerce transactions and widely used offline in place of ID cards or pass permits. In view of such circumstances, contactless IC cards have been used to save labor involving taking an IC card out of a card holding case. Contactless IC cards each have embedded therein transmitting/receiving means (antenna) for transmitting and receiving data wirelessly using electromagnetic waves or the like. By holding the IC card near a dedicated card reader, data is transferred without establishing a physical contact between the IC card and the card reader.
When conducting an e-commerce transaction via a network using an IC card, it is very important to match a value on the IC card with a value at a management server that manages the value on the IC card. Since the values are exchanged between the IC card and the management server via a network that does not ensure establishment of a connection, a card writing process may be interrupted, resulting in a mismatch of values. In particular, in the case of a contactless IC card, establishment of a connection is not ensured between the IC card and the network. As a result, the card writing process may be interrupted easily.
In response to the problems, there is a card writing process sequence that assumes that the card writing process will be interrupted. In the process sequence, when writing a value to an IC card, a flag value is provided indicating whether or not the writing to the IC card has been completed normally. The flag value is stored in the management server or the IC card. Determination of the flag value enables determination of whether or not the writing has been completed normally.
The above-described known technique for determining whether or not the writing to the IC card has been completed normally on the basis of the flag value has the following problems:
(1) In a case in which simultaneous accesses involving writing the value and changing the flag value are not ensured by the IC card, if a card addition/subtraction process occurs offline before the subsequent communication is established between the IC card and the management server, the value on the IC card is changed. Therefore, there is no method for determining whether or not the card writing process has been completed normally.
(2) Since there is no method to deal with a mismatch of values between the IC card and the management server, it is difficult to make a payment settlement via the Internet using a contactless IC card.
(3) When the card writing process is interrupted, the IC card user must communicate with the management server to detect the processing result.
In view of the foregoing problems, in a case in which the value on the IC card does not match the value at the management server, when the IC card is used offline, a value that is not supposed to exist in reality may be available for use or a value that is supposed to exist may not be available for use, resulting in inconvenience in which a desired commerce transaction cannot be conducted.
In view of the foregoing problems of a communication method for enabling communication between a known card (IC card) and a management server therefor, it is an object of the present invention to provide a new and improved communication system, card, management server, and communication method for matching a value on a card with a value at a management server therefor even when a card writing process (value subtraction/addition process) is performed online.